At many places in Pliska, Madara and Preslav, as well as in the monasteries
in Ravna near Provadia were discovered identical groups of characters:

The frequent use of these characters as well as the fact that they do
not occur in strict sequences and are repeated several times in one and
the same inscription points that they designate numbers. But, unfortunately,
they could not be deciphered for a long time.

Some years ago, while studying the inscriptions from the territory of
the former Kubrat Bulgaria, I came quite unexpectedly to absolutely same
sequences of characters. As it turned out, this type of numbers was already
in that area since earliest times - around the V-VI c. BC (see
G. Turchaninov, Op. cit., Supplements). The Proto-Bulgarian characters
depicted the numbers of one, ten, twenty and one hundred - i.e. the basic
numbers, which were characteristic for many peoples.

Equipped with these important data, here is the reading of the various
inscriptions of this type from the territory of our country,:

The interpretation is straightforward and almost all inscriptions were
discovered on goods. Some of them were scratched on (already produced)
dishes and amphorae - the inscriptions recorded the quantity of the manufactured
articles of that type or marked their capacity. The remaining inscriptions
come from clay bricks in Madara and on stone blocks, used in the buildings
in Pliska. In these cases the characters obviously record the total number
of clay bricks, which had been used for building a house or the quantity
of the stone blocks, which had been made by a group of workers. The characters
were written on the inner side of the blocks and were walled in later.
Therefore they were written not after the completion of the building, but
during the preparation of the building and in the course of its construction.